As is well known, an indicator display of conventional design is in the form of a unit comprising at least one reflector in which an incandescent or fluorescent lamp is mounted, and further comprising a transparent glass or globe which is mounted inside the reflector.
Such a display is relatively thick, and gives rise to problems of adapting it to the support on which it has to be mounted, this support being usually a corner of the vehicle or a wing. In general terms, the bulbs or other light sources are fragile, and also have a fairly short working life and a high energy consumption. For this reason, there have already been proposals for indicator displays which are compact, and which employ as the light source a semi-conductor light emitting assembly in the form, for example, of electroluminescent diodes. Such arrangements enable the above mentioned disadvantages of conventional displays to be overcome and offer the possibility of providing, for example, illuminating diodes giving light in both of the colours (red and orange) that are conventionally used in motor vehicle indications, while at the same time being uncoloured when extinguished. This enables an indicator display of uniform appearance to be obtained.
A display of this kind is described for example in the specification of U.S. Pat. No. 4,742,432 and the corresponding French published patent application FR 2 574 616A, in which the electroluminescent diodes are mounted on a flat support element which is overlaid with an electronic circuit consisting of multiple components, with an optical collimating element being mounted over the said diodes. In practice this optical collimating element has a plurality of reflective parabolic cavities which are extended in insulating cylindrical openings that engage closely within conductive rings forming part of the diodes, until the insulating lower face of the said optical element comes into abutment on the support.
When the display is of non-planar, complex shape, the collimating element has to be shaped accordingly for electroluminescent diodes which then define a three-dimensional network.
This then gives rise to problems because a new shape has to be found for the optical collimating element, such that the optical performance of the display always remains excellent. This means that the electroluminescent diodes have to be located in carefully selected positions in order to give a satisfactory light. A further requirement is that the optical element must be mechanically robust and easy to manufacture.